import { useMemo } from 'react';
import Taro from '@tarojs/taro';

export type NavBarMetrics = {
  /** 状态栏高度（刘海/灵动岛上方） */
  statusBarHeight: number;
  /** 导航栏总高度 = 状态栏 + 内容区 */
  navBarHeight: number;
  /** 标题栏内容区高度（与胶囊对齐） */
  navContentHeight: number;
  /** 右侧留白，避免与微信胶囊按钮重叠 */
  navBarPaddingRight: number;
  /** 左侧留白，与右侧对称以实现标题视觉居中 */
  navBarPaddingLeft: number;
};

const H5_FALLBACK: NavBarMetrics = {
  statusBarHeight: 0,
  navBarHeight: 56,
  navContentHeight: 56,
  /** 避开微信内置浏览器右上角 ··· / 设置入口（约一颗胶囊宽） */
  navBarPaddingRight: 96,
  navBarPaddingLeft: 16,
};

const WEAPP_FALLBACK: NavBarMetrics = {
  statusBarHeight: 20,
  navBarHeight: 64,
  navContentHeight: 44,
  navBarPaddingRight: 96,
  navBarPaddingLeft: 96,
};

/** 计算小程序自定义导航栏尺寸（对齐微信胶囊按钮） */
export function getNavBarMetrics(): NavBarMetrics {
  if (process.env.TARO_ENV === 'h5') {
    // H5：在微信浏览器内额外避让右上角菜单；非微信保持较小右侧留白
    const inWechat =
      typeof navigator !== 'undefined' && /MicroMessenger/i.test(navigator.userAgent || '');
    return {
      ...H5_FALLBACK,
      navBarPaddingRight: inWechat ? 96 : 16,
    };
  }

  try {
    const win = Taro.getWindowInfo?.() ?? Taro.getSystemInfoSync();
    const menu = Taro.getMenuButtonBoundingClientRect();
    const statusBarHeight = win.statusBarHeight ?? WEAPP_FALLBACK.statusBarHeight;
    const navContentHeight =
      menu.height > 0
        ? (menu.top - statusBarHeight) * 2 + menu.height
        : WEAPP_FALLBACK.navContentHeight;
    const navBarHeight = statusBarHeight + navContentHeight;
    const navBarPaddingRight =
      menu.width > 0
        ? Math.max(win.windowWidth - menu.left + 8, 16)
        : WEAPP_FALLBACK.navBarPaddingRight;

    return {
      statusBarHeight,
      navBarHeight,
      navContentHeight,
      navBarPaddingRight,
      navBarPaddingLeft: navBarPaddingRight,
    };
  } catch {
    return WEAPP_FALLBACK;
  }
}

export function useNavBarMetrics(): NavBarMetrics {
  return useMemo(() => getNavBarMetrics(), []);
}

/** 仅注入 CSS 变量，供 PageShell / sticky 子元素使用（不加 height/padding） */
export function pageShellCssVars(metrics: NavBarMetrics): Record<string, string> {
  return {
    '--nav-bar-height': `${metrics.navBarHeight}px`,
    '--nav-content-height': `${metrics.navContentHeight}px`,
    '--nav-status-bar-height': `${metrics.statusBarHeight}px`,
    '--nav-padding-right': `${metrics.navBarPaddingRight}px`,
    '--nav-padding-left': `${metrics.navBarPaddingLeft}px`,
  };
}

/** 顶栏自身样式：statusBar padding + 总高 + CSS 变量 */
export function navBarStyle(metrics: NavBarMetrics): Record<string, string | number> {
  return {
    paddingTop: `${metrics.statusBarHeight}px`,
    height: `${metrics.navBarHeight}px`,
    ...pageShellCssVars(metrics),
  };
}

/** Tab 顶栏内容行：左右留白（标题单独全屏居中） */
export function tabNavContentStyle(metrics: NavBarMetrics): Record<string, string | number> {
  return {
    height: `${metrics.navContentHeight}px`,
    paddingLeft: '20px',
    paddingRight: `${metrics.navBarPaddingRight}px`,
    boxSizing: 'border-box',
  };
}

/** 子页/内页顶栏：标题全屏居中，内容区单独留白 */
export function subPageNavBarStyle(metrics: NavBarMetrics): Record<string, string | number> {
  const pagePad = 20;
  return {
    paddingTop: `${metrics.statusBarHeight}px`,
    height: `${metrics.navBarHeight}px`,
    '--nav-bar-height': `${metrics.navBarHeight}px`,
    '--nav-content-height': `${metrics.navContentHeight}px`,
    '--nav-status-bar-height': `${metrics.statusBarHeight}px`,
    '--nav-padding-left': `${pagePad}px`,
    '--nav-padding-right': `${metrics.navBarPaddingRight}px`,
  };
}

/** 子页顶栏内容行：左侧页边距 + 右侧避让胶囊 */
export function subPageNavContentStyle(metrics: NavBarMetrics): Record<string, string | number> {
  return {
    height: `${metrics.navContentHeight}px`,
    paddingLeft: '20px',
    paddingRight: `${metrics.navBarPaddingRight}px`,
    boxSizing: 'border-box',
  };
}